On Fri, 08 Oct 2004 13:38:01 +0100, "Dave Plowman (News)"
wrote:
In article ,
Phil Addison wrote:
Having tried the digital multi-meter thermocouple type, and the 'pocket'
IR type, I can assure you that the IR type makes the task an order of
magnitude easier.
Is it as versatile, though? Maplin do a DVM with temp probe for about a
tenner, and a DVM has many other uses too (if you haven't already got one).
Horses for courses! I have several multi-meters, 1 of which has a
thermocouple K-bead on a flying lead , and a maplin food probe.
The maplin probe was great for checking the core temp of a joint of beef
but when I tried to monitor the meat as it cooked in the oven the lead
melted!! Seems the probe was good for 200C or so, but not the flex
cable. Doh!!
The thermocouple K-bead is accurate in melting ice and boiling water,
but its not very good at measuring surface temperature because of the
difficulty of getting good thermal and mechanical contact between a tiny
near spherical bead and e.g. a grubby 15mm pipe. Before I had my IR that
is what I used for balancing with a 'clever' arrangement of rubber and
aluminium foil glued into a giant clothes peg. It takes time (lots of
it) to rig that onto the pipe of a radiator and then to repeat it on the
other side, not to mention backache - all that kneeling down and up
again.
With the IR, I at first could not get consistent readings, depended
exactly which bit of pipe you pointed it at, or at the chrome valve etc.
In the end I went for the black emitter idea and stuck a square of black
PVC insulating tape to each flow and return pipe just below the valves.
With that I get the same reading each time and it is quick. I can run
round the house with a clipboard and the IR meter measuring each of the
14 rads in 1/4hr or so.
Can you also the temperature of a domestic oven with the IR type? It's
nice to know just how far out a new one actually is...
Sort of. It measures surface temperatures not air temp so you have to
open the oven and point it at the hot walls, and no, it won't work
through the glass door. I use the thermocouple K-bead DVM for the oven -
it measures the air temp and its flex seems to stand up to the heat, and
is thin enough to close the oven door on it.
Phil
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